First Battle of Bull Run

The First Battle of Bull Run was the first major battle of the American Civil War, fought at Manassas in northern Virginia on 21 July 1861 between Irvin McDowell's invading Union army and the defending Confederate army of P.G.T. Beauregard. In the ensuing battle, the Union's first attempt to capture Richmond was halted and defeated due to the strong defense of the Confederate line by Thomas J. Jackson's brigade and the ensuing Confederate counterattack; Jackson earned the nickname "Stonewall" for his resolve. The Union army routed back to Washington DC, and no more major battles would be fought in Virginia for the rest of the year.

Background
Months after the Battle of Fort Sumter on 12 April 1861, President Abraham Lincoln ordered Union general Irvin McDowell to lead the 35,000-strong Army of the Potomac south from Washington DC to crush the Confederacy in one swift blow by capturing their capital of Richmond, Virginia. The Union army was inexperienced, as was General McDowell, but their Confederate opponents across the Potomac River were just as unseasoned. P.G.T. Beauregard's Confederate Army of Northern Virginia, with a strength of 32,000 troops, marched north to Manassas junction after being alerted of the Union invasion plans by Confederate spy Rose O'Neal Greenhow, who was based out of Washington. The Union army halted on the north bank of Bull Run Creek in Prince William County, just across from the Confederate army's positions at the Manassas road junction. On 18 July 1861, the Confederates repelled Daniel Tyler's reconnaissance-in-force in the Battle of Blackburn's Ford, forcing McDowell to plan a frontal assault against the Confederates.

Battle
On 21 July 1861, McDowell decided to launch his attack. Large numbers of Washingtonians travelled 25 miles to spectate the first battle of the war, bringing champagne and picnic baskets to the nearby hills. 18,000 Union troops attacked the Confederate left flank, driving the rebels back from one position to another. Union victory looked so sure that, one one part of the battlefield, Union soldiers stopped to gather souvenirs. However, at the center of the southern line, Thomas J. Jackson's Virginia brigade held firm against the Union advance, and Confederate general Barnard E. Bee said that Jackson was standing like a "stone wall", and Jackson came to be known as "Stonewall". At 4:00 PM, Beauregard ordered a counterattack which turned the tide of the battle, and Jackson urged his men to give the terrifying "rebel yell". Confederate reinforcements under Joseph E. Johnston began to arrive by horseback and train, as Robert Patterson had failed to stop their advance after the Battle of Hoke's Run. Union guns became entangled with the carriages of fleeing spectators, and the Union retreat turned into a rout as the Union launched a disorganized withdrawal towards Washington DC. The bloody first battle at Bull Run dispelled the public's expectation for the war to end within a month, and they realized that the war would be longer and more costly than anticipated.